Original subtitles

Narrator: A distress signal is overheard from deep in space.

Podlaskaya: Sounded like she was talking to somebody.

Narrator: Authorities deny it ever happened.

The soviets were anxious to cover up some of their mistakes.

Narrator: Voices of the dead torment soldiers in vietnam.

Very much like somebody coming from the beyond.

Narrator: Do these spirits have a message for the living?

Dr. Kislenko: He tells them,

"it's time to leave before you die."

Narrator: Massive thunderclaps come out of nowhere,

But there is no storm in sight.

I mean, you got to run for the hills

When you hear something like that.

Narrator: Endless streams of data,

Information bombarding the planet from within

And from the furthest stretches of the universe --

What messages do these phantom signals hold?

-- Captions by vitac -- www.Vitac.Com

Captions paid for by discovery communications

♪♪

1960 Italy.

Battista brothers achille, a cardiologist,

And giovanni, a forensic scientist,

Build their own radio listening station

In an abandoned world war ii bunker

Using scavenged and borrowed equipment.

They claim to have intercepted communications

Of russian and u.S. Astronauts to their ground controls.

Though intriguing, most of the broadcasts are routine.

But then something else, something chilling.

The battista brothers had multiple claims

That they had a tracking station

Which gave them the ability to track

Low earth orbiting satellites or manned space travel.

Among some of their larger claims,

They had a recording of what seemed to be

The last words of a soviet cosmonaut.

[ woman speaking indistinctly ]

According to their claim,

The spaceship was flying away from earth in a trajectory

That didn't take them across the horizon,

Just pointing away so the signal kind of just slowly died out.

Among other things, they had what sounded like a heartbeat,

Sounded like someone breathing, potentially,

And there was also, I believe, a transmitting s.O.S. Signal

That didn't have the doppler effect.

So it means it was traveling away from earth

Because it kept getting quieter and quieter and quieter.

Narrator: The brothers claim this secret communication

Is the last transmission of a cosmonaut

Trapped in a doomed spacecraft floating helplessly in space.

The soviet government denies the existence of any manned missions

Prior to the flight of yuri gagarin in 1961.

But rumors of early space flights

Ending in disaster haunt the soviets.

Nass: Right, so I guess the concerning thing

For a lot of people at the time

Is that we're in a situation where the soviets

Are potentially putting people into space

In a kind of undocumented fashion.

If that were the case, then it would be a cover-up.

Dr. Kislenko: The idea that the russians would lose cosmonauts

As part of their training program in general

And then specifically in space is plausible.

It's not out of the realm in part because

We don't know everything from soviet archives.

The space race was one of the most competitive times

In u.S. History and russian history.

And what drove that in many ways was the competition

Between the russian space program

And the american space program

To demonstrate the technological capacity

To be able to send humans to space.

Again, the russians beat the americans

By literally probably a month or so.

Dr. Kislenko: If you could be the first to conquer space,

It reinforces the idea that your state has a tremendous amount

Of potential capacity and integrity to it.

It was a tough time because you were looking for those firsts,

You know, the first spacewalk,

Dr. Kislenko: The soviet union was always an enormously secretive society

Of keeping all information to a very bare minimum

In closely guarded hands to preserve this idea

That the ideological experiment that was the soviet union

Was undefeatable, that it was perfect.

But we have no real corresponding evidence

In terms of documents, even defectors that came out.

We lack that sort of smoking gun, as it were,

To say definitively these guys were in space.

Narrator: But if the recordings are real,

The brothers have evidence that russia launched

Two or more manned space flights prior to gagarin.

If they're not, where do these transmissions come from?

Is this a distress call from somewhere else?

Whether or not people were eavesdropping and able

To hear something different, I don't know.

Narrator: Between 1960 and 1964,

The brothers supposedly record thousands of hours

Of both telemetry and communications

From missions including sputnik, vostok,

And even the u.S. Mission explorer.

The soviets dismiss the battista brothers' claim as a hoax.

But still, the haunting russian voice of the distress call

Was not so easily forgotten.

The distinct things that I was able to catch

On the first try --

She was counting down.

She was saying, "three, four, five, three, four, five."

She also said, "okay, okay,"

The word that you use

When you respond to somebody talking to you,

And you acknowledge that you understand

What they're saying.

Based on the tone of her voice,

It sounds like she was listening and responding.

So it wasn't just her speaking independently of anybody else.

It sounded like it was within the context of a dialogue.

In the middle of the clip,

That's when she was most agitated.

In her tone, it didn't come out

That the distress was due to any kind of emergency

Or unsafe situation.

I think it sounded more like

She was trying to reiterate something louder

Because she wants to be heard.

Narrator: A few years later, on July 20th, 1969,

America would be the first and only nation

To land a man on the moon.

This incredible achievement inspired an event

That would suddenly call into question

The soviet dismissal of the battista brothers' claims.

A pair of amateur radio enthusiasts in kentucky

Are directly listening in on the highly anticipated mission.

Larry baysinger, former military radio technician,

And journalist glenn rutherford

Tapped the frequency of 12-watt radios using vhf radio.

They bury 6,000 square feet of copper plating in the backyard

To ground the equipment.

The antenna is made from chicken wire and aluminum,

The radio receiver from a korean war tank

Found at an army surplus store.

Baysinger makes some adjustments.

Aiming the antenna at the moon made more difficult

Because it's a cloudy night,

They manage to record 35 minutes of the moon landing.

By and large, we're just throwing signals

Out into the air all the time.

If you had the right equipment and set it up,

You could intercept those signals

And hear what was being said, at least by the astronauts

When they're talking back to earth.

Nass: He built his antenna basically with scratch-built material.

He's using wood for some of the stabilizing arms.

And from all of his effort,

He was able to build a beam antenna for receiving signals

That were coming from the moon.

Back then, most of these transmissions were unencrypted.

They were just basically able to receive them

Using army surplus equipment.

Assuming that there was something in low earth orbit

Or in a launch trajectory away from earth,

And they had an appropriate transmitter

Capable of reaching earth,

I don't see any reason why that there couldn't be someone

On the ground picking up those signals.

Narrator: The two listen in, amazed by their success

As astronauts speak to president richard nixon

And remark on the play of shadows on the lunar surface.

So larry's listening to the vhs signal

Directly from the moon, so he heard it first.

He heard it seconds ahead of when it got turned around

By the news stations and sent out.

Narrator: Is it conceivable that in the 1960s,

Amateur equipment

Assembled and monitored by casual civilians

Could pick up russian space program transmissions?

Nass: Radio, in a simplified description,

Would be imparting information onto a radio signal

That you're using some kind of antenna to push out.

Receiving would be the antenna is picking up the signal,

And that is then getting pushed out into the speaker

That you're listening to, or the headphones.

Narrator: In the early space race years,

The communication systems from the vostok mission

Are based on vhf communications,

143.625 megahertz,

But also on shortwave communications

Using strong transmitters

Belonging to the ussr ministry of communications.

Even today, 45 years after the end of the space race,

Radio frequencies are easily captured from space.

Nass: Just as a demonstration,

We can set up a simple antenna that doesn't even move,

And it will just pick up the signals

That are being downlinked by the satellite.

So right now, we're trying to catch the downlink

Of the upcoming noaa weather satellite path,

Which goes from south to north.

It's downlinking a rf stream that we're gonna pick up

And convert back into an image file

Which we can see on the screen for weather patterns.

As the satellite's passing overhead,

It's basically going to be downlinking different images

That it's captured as it's gone over the world,

Basically, to show interesting weather patterns

For the national weather service.

This is 137 megahertz,

Which is the same space of frequencies

That is used today by low earth orbiting satellites

And manned international space station-type satellites.

Larry has a recording of an apollo mission.

It is likely that the battistas could have recorded

Something else which happened later

When technology improved a little bit

During the cold war.

Narrator: So if it is possible to intercept such a signal,

Why are the soviets denying the entire existence

Of the transmission and the event?

If you fail, it obviously casts a pall of doubt

Over whether or not

You have the technological acumen that you claim to do.

Nass: At the same time, the soviets

Could just easily say, "eh, never happened."

And that's exactly what they did, right?

They said, "nope, we don't know anybody like that.

We've never had anybody on the books like that.

Narrator: Were the phantom transmissions picked up

By the battista brothers

Really the dying words of a soviet cosmonaut?

In this cloak-and-dagger era, how far will the russians go

To make sure no one posed a risk to their plans?

Narrator: 1960.

Two italian brothers build a radio-listening station

In an abandoned world war ii bunker,

Claiming they've picked up russian space mission

Radio signals.

But things take a much darker turn

When they intercept what they describe

As the dying words of a cosmonaut

Trapped in a failing spacecraft.

[ woman speaking indistinctly ]

Dr. Proctor: I think the last thing that they ever would have imagined

Is that they would pick up a transmission

Of the last moments of someone's life in space.

Many people thought that there would be tragedies

Exploring space.

Dr. Kislenko: People died on a fairly routine basis

Because of technological and scientific error,

Programing problems, pilot error,

Whatever you want to call it.

I'm absolutely convinced soviet leaders at the time

Were saying, "we cannot afford the public to understand

That we make mistakes

Or that we're gonna own up to our mistakes,

Because then anything's fair game."

Narrator: Recently declassified documents reveal the soviets

Are potentially covering up multiple cosmonaut injuries

And deaths -- more than previously thought.

When we talk about the space race for either country,

You're in a whole world of conspiracies.

The so-called sochi six is rather notorious photograph

Taken of the elite graduating class of soviet cosmonauts,

And it has been doctored over time to remove some people

From what I think originally was 11 astronauts down to 6.

Narrator: Why are only some of the cosmonauts' faces

Physically removed from these photos?

At the core of it is this notion that there were cosmonauts

Who died in orbital flight missions

Before yuri gagarin in 1961.

This was not the first time the soviet union

Had doctored photographs.

It's not just that they died. Some of them never existed.

They're erased from history.

And they do that to make it very clear

That there's one narrative in soviet history.

Any failings along the line of that official narrative

Were seen to be either counter-revolutionary

Or to challenge this notion of soviet supremacy.

Narrator: With these and even more rumors

Haunting the soviet space program,

What would be the repercussions of the cold war?

You can imagine the impact in a place like the soviet union

Where the same revelations aren't just gonna be sad

Or bring up questions about cost or, you know,

That it's gonna speak fundamentally to the regime.

If the russians had a mistake or something went wrong,

They were not gonna let that out

Because it was all about success.

Doesn't take much to logic through that and say,

"well, if you've made a mistake

And I can question your validity,

Then I'm gonna do it in a lot of other ways,

Like whether or not you should be the only party

And whether or not you should be the government."

Narrator: Out of fear of appearing vulnerable,

Could soviet government officials actually keep

The deaths of cosmonauts completely covered up?

There were a lot of things that the soviets did

That we still don't fully understand,

Even with the release of documents and archives

And discussions with people in the period.

Nass: What bothers me the most about it is if it was a hoax,

Tracking that stuff, I find interesting enough.

It didn't have to be sensationalized

Into possibly a cover-up.

Either it's bad because the soviets actually did

Cover something up,

Or you had these brothers that were possibly doing this

For fame or some kind of attention.

Dr. Kislenko: We need more evidence.

We lack documentary evidence to suggest

That any of the cosmonauts died in secret missions

That were never announced to the public.

We have a couple of documents that say,

"let's keep soviet failures down to a minimum,"

But that doesn't necessarily confirm

That the soviets were in space

Before they say they were in space.

Narrator: Though the iron curtain fell in 1991,

Many of the records remain classified or missing.

I think any time you're engaged in this kind of,

You know, tremendous exploration of the unknown,

There's going to be this kind of doubt.

Narrator: We may never learn the full details

Of the russian space program

Or how many cosmonauts were lost,

But they will never be forgotten,

Due in large part to the early radio experiments

Of the battista brothers.

On the evening of February 10th, 1970,

In the jungles of vietnam,

A horrible wailing torments the people of hau niga province.

[ howling and thumping ]

♪♪

The sounds of people screaming,

Crying, gongs banging,

And a child calling for her father

Are followed by a clear message

That came from the voice of a dead vietcong soldier.

"my friends, I am dead."

Then a warning to his former brothers in arms

To turn back and give up the fight.

Dr. Kislenko: Pretty scary.

Very much like somebody coming from the beyond,

In this particular case coming from hell.

He's wondering.

He's basically, at least initially, unclear

Whether he's alive or dead

And making a very emotional appeal

To fellow soldiers in the field

To stop fighting before it's too late.

Narrator: If the spirits of the dead can reach out to the living,

Could the jungles of vietnam really be haunted

By the ghosts of their dead comrades?

Dr. Kislenko: It's very powerful. It is scary.

This is like the twilight zone.

Narrator: Or could the horrible wailing sound

That threatened to drive these men to madness

Have another meaning?

Narrator: By the late 1960s,

The u.S. Is embroiled in a terrible war in vietnam.

Thousands of casualties are inflicted on both sides

As the conflict spirals out of control.

The conditions for this particular war

For both sides were horrific.

If the jungle doesn't get you

With disease and rain and leeches and insects,

Obviously the enemy will.

And this was not easy warfare,

Just sending in 3,000 tanks in a field.

This was getting down and dirty in a very inhospitable jungle.

So the vietcong soldier who was used to all the jungle sounds

And can sleep through it

Is now hearing something they have no experience with.

Dr. Kislenko: These things happened in the middle of the night.

You know, you can imagine it's absolute silence,

It's pitch dark, and then pretty much out of nowhere,

You hear this dreadful sound echoing.

[ howling ]

Dr. Fallah: You hear a sound. You look.

You start saying, "is it there, is it there?"

And then when there's nothing to see,

Your mind starts trying to make sense of the world.

So what could it be

That you can hear but is invisible around you?

Narrator: It is the vietnamese belief that the dead must be buried

In their homeland,

Or their soul will wander aimlessly in pain and suffering.

So when you die, your soul goes,

And that's why it has to be properly accounted for.

You need that burial to take place.

It needs to be commemorated. It needs to be in your homeland.

And if it's not, your soul wanders.

And that is the worst hell on earth for vietnamese.

Somewhat, I guess, to christians

Worrying about being in limbo forever.

Your cultural background goes a long way

Into your normal everyday experience growing up,

Which also goes a long way into

How you make sense of the world around you.

Scorpio: It's a buddhist belief that you're bound to your homeland

And your family.

You might have lived in the same village

For five or six generations,

So you have a very, very strong connection to that land.

Dr. Kislenko: And what they come to do is to,

In effect, worship dead ancestors.

They offer food as well as sometimes money

And other goods to the dead as a means of appeasing them

And honoring them.

In the mind of a vietcong soldier,

If you're hearing these voices,

There's already a cultural aspect

Where you expect to be

More connected with the spirits in the world around you,

That there's this idea there are spirits.

These are profound beliefs in vietnamese religion

And vietnamese culture.

And that's a big part of what these boys

Fighting in the jungle believed in.

And then that might lead to this idea,

If you've grown up in a culture where there are more spirits,

There are things you can't see in the world around you,

That you might start attributing it to other things like that.

Narrator: If these are the voices of departed soldiers,

What message are they trying to get across to the living?

Dr. Fallah: These sounds that we're talking about

Weren't terribly clear to begin with.

They were a little hard to hear and understand

So that you've got this kind of series of possibilities

For what that sound can be.

And then within a few seconds,

They're talking to you as a person,

As a fellow soldier, asking you, "why are you fighting?

Why are you still here? Why don't you go back home?"

Dr. Fallah: A rational person who's rested

Easily comes into, "well, these aren't real,"

But they're in a stressful situation

That causes that noise to increase

And opens up the number of possibilities

From their own memory and experience to draw upon.

Scorpio: If you combine their spiritualism

And their belief system, I can easily understand

That they would be in a state of confusion

And totally believing that that's real.

Narrator: The mysterious voice heard in the jungle appeals

To his vietcong brothers.

It tells them to go home.

"this is your chance to leave before you die

And wander the earth

Because there is no one to bury you."

Moaning, the groaning, the dialogue from a dead soldier

Who you can identify with,

And in the middle of the darkness,

In the middle of a war which you know

You have a pretty good likelihood of getting shot at

Or getting killed, that must have been terrifying.

Arama: I don't know how I would have reacted myself

If I was one of those vietcong troops

With their belief system.

I think I might have run as fast as possible in a state of panic.

Narrator: But even if just one soldier experienced

Hearing a ghostly message,

How could the same event be reported by an entire group?

So the idea of mass hysteria, when somebody is stressed out

Or under some physiological change that they can't explain,

Other people sometimes end up feeling the same way themselves.

When you're sitting in a group of people,

You end up getting to an average emotional state

Based on everybody involved.

So if everybody's anxiety raises a little,

The average raises a little.

You get this kind of infectiousness.

When you have a lot of people starting to make that report,

Then you got to think that it's not about an individual.

It's not a single type of stressed person going crazy.

It's more that there's got to be something else

That everybody's experiencing such that a number of them

Experience it so strongly that they're willing to speak up

About it to everybody else around them.

So even the most educated and trained and scientific of us all

Are suspect to that kind of fear factor.

Dr. Fallah: I do think that there's a lot

We don't understand in the world,

And we don't entirely know what is going on.

When we don't understand something,

We have generally put it in the realm of the supernatural.

Narrator: Could these be the voices of the dead pleading

For their comrades to save themselves,

Or is there a darker origin to these recordings?

Narrator: In the jungles of the vietnam war,

A horrible wailing torments the people of hau niga,

The sounds of people screaming,

Crying, gongs banging,

And a child calling for her father

Are followed by a clear message

From the voice of a dead vietcong soldier.

"my friends, I am dead."

Dr. Kislenko: If you're in the jungle at night,

You hear horrifically ghostly sounds,

You hear moans, you hear groans, and then you hear somebody

Talking to you as if they're dead,

Which makes you think, as a vietcong soldier

That it's one of your comrades and, of course,

Could be you at any particular moment.

Narrator: Are the jungles of vietnam haunted,

Or are there other forces at work?

Perhaps we can find a clue in the fact that the sounds

Seem to start appearing at a specific time in the war.

I think the invading force obviously would have

Had more technology and maybe bigger numbers.

So that's probably helping their adrenaline a bit.

But it might have been a false adrenaline in a sense, too,

Because the vietcong troops --

They would have been totally accustomized

And acclimatized to the surroundings,

Easily 1,000% better than the americans.

So you hear the sound in the woods,

And you're in a ditch with your comrade,

And you're gonna look around first

To see where it's coming from, because if you can see

What it is, you can make sense of it.

Then you start getting into increasing your stress levels

And your concern about it.

Dr. Kislenko: So you are constantly afraid,

And that's where the conditions are really ripe

For messing with your mind.

And that's precisely where the americans come up

With psychological operation.

Narrator: Ghost tape number 10

Is part of a recently declassified

U.S. Psychological warfare campaign

Known as "operation wandering soul."

Nass: So then we find out about ghost tape number 10,

Which was basically a collection of voices in vietnamese

Saying things like, "this is your ancestor.

Stop doing what you're doing 'cause you're going to die."

Dr. Kislenko: There's a variety of messages.

This is not just one.

There are messages of pretty simple ones, right?

"run away. Come to us. We're gonna win this war.

You're fighting the americans

Who, you know, have superior technology

And training, and they'll kill you."

The one that's sort of most famous and most haunting

Is this idea of, you know, the displaced soul.

Various sources will tell you that it started in 1970,

But there are historical records about using similar tapes

Much earlier than that in the 1960s.

Some will tell you it was only used in south vietnam,

But we know for sure that they were used

In places like laos and cambodia, too.

Nass: Later, we find out that they, of course,

Were using them with p.A. Speakers.

They were connecting them onto helicopters

And flying around areas

That they thought there might have been the north vietnamese

And using that in possibly an effective way,

Although it's never been claimed by the north vietnamese

At all at that time or later historically

From people who were fighting at the time

That it had an effect of actually scaring them away

From their course of action.

Arama: If you combine their spiritualism

And their belief system,

You'd be shocked at how people start to think

And start to hallucinate.

Narrator: U.S. Engineers spend weeks recording eerie sounds

And altered voices which pretend to be

Vietcong killed in action

For use in the operation with the intended purpose

Of instilling a sense of turmoil in the enemy.

The resulting tape, dubbed "ghost tape number 10,"

Is played on loudspeakers outside u.S. Bases

And sometimes from patrolling helicopters.

The voices call on their descendants in the vietcong

To defect and cease fighting.

Who would want to hear a ghost story

When you're in the middle of those conditions, right?

It's like, you know, when you're a kid at a campfire

And you get spooked by a ghost story.

You know, this is ten times worse, right,

Because there's actually people out there trying to kill you.

It's this super-sensory overload

Because you're not able to control it.

When your body and your mind

Has gone through that level of stress,

You can't push things aside as easily

As you could otherwise, and it's those type

Of environments that lead people to snap.

Arama: A big debate among survival experts

Is what's more important,

The psychological or the physiological?

I think most research points at the will to live

In the psychological as the key,

'cause the minute you panic, you're dead.

Narrator: The stress of jungle combat conditions for the vietcong,

Primarily sleep deprivation,

May have also worn down their psychological defenses.

When you have sleep deprivation, starvation, severe dehydration,

Those all play into your psychology.

When you're deprived of all the basic essentials

For physiological survival,

Your brain does go -- it goes wacky.

But hardly any of the experts talk about sleep deprivation

Because it's so abstract.

Sleep deprivation changes our control

Or the steadiness in our brain.

Normally, we kind of have a signal

Where we vary in a small range when we're rested

And have right nutrition.

But when we're sleep-deprived,

We get these high variabilities to everything going on.

And that means things that so far out of range

From our normal experience,

You might think are really happening.

Arama: And all of a sudden even the so-called expert

Is hearing things and have no idea what it is,

'cause they're hallucinating, they're delusional.

Their mind's not gonna operate

The way a normal person's mind will.

They're gonna be susceptible to suggestions.

They could have psychotic breaks.

They could exhibit hallucinations

Like schizophrenia.

Arama: Your body has to rest to replenish everything

And make good decisions.

So if you're seriously sleep-deprived,

You're gonna make the worst choices.

And that's what we call the domino effect,

And it leads to worse choices and death.

The stress means every little thing

Is going to have a major impact on you.

And how do I trust the men next to me in the war

If they're starting to go crazy?

Narrator: "wandering soul" is part of the official effort

To convince the vietcong to surrender.

Unofficially, the american troops

Tried many different psyops tactics

In their attempt to accomplish this task.

Dr. Kislenko: The american playing-card thing,

Which is featured in many vietnam war-style movies,

Is the calling card for death.

Dr. Fallah: If you can win the battle of the mind

Before you get into the physical battle,

You're going to have an advantage.

It's like, you know, the maori when they famously

Go into battle doing their tribal dances,

Making faces, right, at death.

Dr. Fallah: The maori use the haka

To try to intimidate their opponents

Before engaging in battle.

That sends a psychological signal

About the kind of enemy you're fighting.

Narrator: This isn't the only attempt

By the american psyops division to terrify the north vietnamese

Into surrendering.

Dr. Kislenko: Very, very famously,

One of the ghost tapes involves tiger sounds.

[ growls ]

There are rumors that americans took a tiger scream

And then put it on tape

And then went out into the jungle,

Having already circulated among soldiers

The notion that they were tigers

And then later that night

Broadcast this manufactured tiger sound.

[ tiger growls ]

Narrator: So what is the impact of this psyops tactic?

Arama: It was guaranteed there was an effect.

I would say that the americans were very smart

To do what they did because there's a good possibility

That it would have reduced the morale,

At the very least.

Dr. Kislenko: According to american documents,

There were several thousand defectors

Over the course of the late 1960s and early '70s

Under investigation revealed that they were at least in part

Motivated by these ghost tapes.

Narrator: While it's hard to measure

The success of operation wandering soul,

The tapes undoubtably put fear in the hearts

Of whoever heard them.

Every night they played, the jungles of vietnam

Came alive with the voices of the dead,

Convincing some soldiers to put down their weapons

And return home to their families.

November 14th, 2017.

911 emergency lines are inundated with calls

From 15 counties in alabama.

Residents reported hearing a loud boom...

[ boom ]

...Like an earthquake or a cannon...

[ boom ]

...Coming from the sky.

I can't imagine how terrifying it would be to be standing here

And suddenly hear a huge explosion or booming sound...

[ boom ]

...And as I look around,

Not being able to see the source of it.

There's just this loud cracking boom.

[ boom ]

Witnesses describe what essentially

Sounds like a large cannon boom.

[ boom ]

Almost like an earthquake, but it's above.

Narrator: The national weather service announced

That they couldn't explain it,

As did the national geological survey and nasa.

The massive boom didn't appear to have a natural source.

[ boom ]

What was it?

The answer, it seemed, lay in a centuries-old phenomenon

Known as skyquakes.

Skyquakes are a phenomena where there's a very loud noise,

But when you look around,

There's nothing obvious that's causing that noise.

The booms are extremely loud, so loud, in fact,

That they often set off car alarms.

[ car alarms blaring ]

And you can imagine that people were like, "what was that?"

What happens when there's thunder

But no clouds in the sky?

Where is that coming from?

Narrator: What is behind these baffling sounds?

Pre-science, people would have been terrified.

They would have thought that it was a voice from god

Or some kind of bad omen.

A loud crack, a boom, a growl, a rumble,

Some sudden, abrupt noise.

It's just coming from somewhere out there.

You can hear it distinctly, but you don't know why.

Narrator: Skyquakes appear to have no connection to the weather,

But could these behemoth sounds be coming from the earth?

Or are they the product of some unknown presence in the skies?

Narrator: Residents in 15 counties in alabama

Flooded the 911 emergency system in November 2017,

Reporting mysterious thundering sounds coming from the sky.

[ boom ]

The best explanation that can be found for the terrifying boom

Was that they were a mysterious phenomenon known as skyquakes.

[ boom ]

They are heard in every part of the planet.

They strike out of nowhere.

[ boom ]

There is no apparent link to the source.

What theories could possibly explain their origin?

One of the more compelling explanations I have heard

Is that these skyquakes are caused by earthquakes.

Mckinnon: The earth is moving all of the time.

Tectonic plates on the surface of the earth

Are moving about the same rate your fingernails grow,

So they're creeping along.

They get stuck, and they break.

It's kind of like when you snap your fingers,

You're building up the stress tension

Until it overcomes the friction

And you hear it in the form of a snap.

So you can imagine taking something like rock

That is fused together

That's under a tremendous amount of strain

And then slipping and breaking.

A majority of the energy released by earthquakes

Are actually released by shallow earthquakes,

Which are earthquakes that are happening

Closer to the earth's surface

Than ones that we typically think of.

It can be possible that an earthquake will occur,

And we won't feel it, but it can produce a sound.

An earthquake generates a couple of different types of waves.

One of them is a "p" wave, a pressure wave,

Which is like if you're splashing water

And it moves and pushes,

The next one that follows is the "s" wave,

The shear wave, that's moving back and forth.

So if you take a shoelace and wiggle it,

That would be the shape of a shear wave.

When pressure waves are moving the earth,

That earth is then vibrating almost like the skin of a drum

Or the membrane of a loud speaker

And causing the air to also vibrate.

It transmits that wave from earth to air,

Which then people can hear.

That means that the bigger the earthquake is,

The bigger the amplitude of that "p" wave,

The louder it's going to be.

Things like how cold or how warm

Or how much moisture in the air can affect

How sound propagates through the air.

Mckinnon: Sound propagates in all sorts of different ways,

And it can travel through rock.

Rock doesn't block sound.

In some ways, it can even amplify sound

Depending what the frequencies are and what your geology is.

The cool thing is that because sound is an energy

And it's propagating out,

It can be subject to the dynamics of the atmosphere.

It can bounce those vibrations around and transmit them

Into places you wouldn't expect.

If we use krakatoa as an example

Of how you can have a distant phenomena

And that sound under just the right conditions

Travel what seems absurdly far,

Then suddenly it starts getting a lot more plausible to look at

Maybe it's some earthquake or landslide

Or eruption or meteor or explosion somewhere else

That's under just the right conditions

So that sound is traveling very, very, very far.

Dr. Hayes: This is one possibility that has some merit,

Although my understanding is that it's harder

To track these ones and that they don't seem

To follow typical patterns of earthquakes.

Narrator: While this explanation would seem like an easy one,

It fails to explain how some skyquakes

Don't have seismic readings to accompany them.

Breaking the sound barrier could definitely create a boom

Where you can't immediately tell what the source is.

A sonic boom is when something is traveling faster

Than the speed of sound, so instead of sound waves

Just propagating out sort of in all directions,

All the sound waves build up and it arrives at you at one time,

So you get a very loud noise all at once.

And it can be enough to rattle windows

And can travel over quite large distances,

Narrator: Is human technology behind this bizarre phenomenon?

People have heard skyquakes around the world for centuries.

Sonic booms are an interesting theory,

But they don't really hold water

Because there's been testimonies about skyquakes

Going way back before jets were even invented.

Narrator: But again, this theory has holes in it.

What could cause sonic booms in the centuries before jets?

There must be something in the atmosphere

Creating this percussion.

Sparling: The vast majority of objects

That do enter the atmosphere explode in the atmosphere.

Often large meteors, if they do enter the atmosphere,

They're entering at supersonic speeds.

They produce sonic booms

If they're large enough of immense proportions.

Especially during the daytime when meteors enter

The earth's atmosphere, it's not always visible

Because of the the sunlight in the bright sky.

We don't see the the streak of light associated with it.

There is a potential for space objects to enter the atmosphere

And cause a loud bang.

Nothing makes it to the ground,

But you would have -- if you were standing near it,

You would have the perception of something exploding

Or a huge bang above you,

But no resulting cause would be visible.

Dr. Hayes: That might be an explanation for some,

But it just doesn't seem to account for all of them

And for the diversity of them around the world.

The world is full of infinite possibilities,

And all of science is trying to narrow down

To the most likely.

There may be an angle in skyquakes

That we can relate to ufos or extraterrestrial visitation.

There is a long history of people seeing ufos

That vanish in the blink of an eye.

Viggiani: And some ufos have been tracked

At speeds of over 7,000 miles an hour.

Dr. Hayes: I assume that if they are visiting earth,

They've learned to exceed the sound of speed long ago,

And this is not a problem for them.

Maybe they're playing around with the atmosphere.

Maybe they're playing around with the physical reality

Of what we see,

And they're just creating weird effects.

There's all kinds of things that might be accounting for that

If you consider extraterrestrials

As responsible for that.

Narrator: When we hear something strange from above,

We look to the sky for answers.

But is it possible the answers are right beneath our feet?

Narrator: Theories abound as to the origins

Of earth-shaking booms erupting from the sky.

Some believe these sounds come from ufos.

But is the real origin more earthly?

Very few, if any, reports that I've ever read

Describe any loud sound as a result of a ufo.

Dr. Hayes: At first it seems plausible maybe,

Or it seems exciting or enticing.

But when you really start to get into the mechanics of this

And you get into the history of ufo sightings

And what those usually actually comprise,

They're quite different phenomena.

And under those circumstances, you would think

That there would be some displacement of air

Or some sort of shockwave.

But very few of the incidents that have reported to me

Have reported any kind of percussive sound at all.

Narrator: If the source of this phenomena

Does not originate in the skies,

Is the answer lying in wait for us at the bottom of the ocean?

Most, or all, skyquake reports

Happen near a large body of water,

Possibly because this helps the sound to travel.

You might think that there's nothing happening

Below the surface of the ocean,

But there's a tremendous amount of things happening.

Mckinnon: All sorts of things are happening underneath

The ocean surface at any time.

We're only seeing the waves up at the top,

But underneath is an entire rich geologic world.

There are volcanic eruptions that happen underwater.

There are earthquakes. There are landslides.

There are pieces of volcanoes that break off,

And you have a flank collapse.

All of these things are happening underwater,

And sound travels really well underwater.

There's some layers of the ocean

That conduct sound incredibly well.

They act almost as a wave guide, bouncing the signal along.

But the thing about that is

It would also register as an earthquake.

Mckinnon: It looks like a sharp jolt

And then chaos as the smaller pieces crumble out,

And it fades off fairly quickly,

Just like if you had a stack of books and you drop them.

It's loud boom

And then the pieces kind of tumbling off to the sides.

And you get the quieter pieces falling down,

You see the same thing in the seismic signal.

Dr. Proctor: Seismometers are extremely sensitive,

So even though it might happen in a remote part of the ocean,

Most likely we're gonna pick that up.

We've got a lot of seismic sensors,

But we don't have a whole lot of the hydrophones,

Which you can think of as being

A really highly sensitive 3d microphone underwater

That can pick up vibrations in any direction

And tell you what direction it's coming from,

How big it is, what frequency it is, what does it sound like.

And if you've got your three points, you can back trace

And triangulate back to where its source was.

But the oceans are really, really, really big.

So even though we have a global network,

It's still possible to have places that we're missing.

Narrator: Could there be any easy answer to skyquakes,

Or is the truth murky?

I think it's comforting to people

To have one solid explanation for something.

Something happens, and there's one single cause.

It's just easier to wrap your head around.

Kosiba: Science is always growing,

Otherwise it would be a really boring field

If we just figured everything out

And we could explain everything.

Just because there's not an easy explanation right away,

That doesn't mean that you're not working towards it.

Sometimes we can take folklore and story as hints

That we should investigate more.

There's a story of the day the mountain moved

In the rocky mountains of canada,

And it turns out it was a loud cracking noise

That when investigated later,

There was a landslide where there hadn't been one

The last time people went through.

And then one day there was a giant landslide,

The frank landslide, one of the most deadly landslides

In canadian history, and the mountain moved again

As it cracked and rumbled and buried the town.

We could have used those stories as a warning,

As a precursor, as a way of exploring more.

Dr. Proctor: There's most likely not one explanation

For all of the different types of skyquakes we hear about

From around the world.

Mckinnon: We definitely know landslides create large, rumbling booms.

We definitely know earthquakes can be acoustic.

We definitely know that meteors, when they explode in the air,

Can create a sonic boom.

All of these are things we've seen, we know,

We have observed repeatedly, we understand.

If we actually do solve this mystery,

It's probably going to be the result

Of several different things happening.

Mckinnon: Although we're recording data all of the time,

We don't always know what to look for.

There's so much happening that we're trying to find a signal

In all of the noise.

Narrator: The next time you hear a boom coming from the sky,

You might want to duck for cover or brace yourself,

Because despite all our understanding of science,

The world around us continues to be

Both awe-inspiring, terrifying,

And beyond our control.